He has faced mounting criticism of his leadership and a corruption probe unearthed fresh allegations of misconduct this month.

But the former ANC security chief retains strong loyalty among many party members and politicians, and easily survived a vote of no confidence in parliament on 10 November.

However, that vote was called by opposition politicians from the Democratic Alliance (DA) party. At the time, commentators said that though a significant number of ANC officials wanted the president to resign, no one wanted the party to be pushed into a decision by outsiders.

“He is hanging on while it is clear that large sections of the ANC … no longer want him as president … The countdown for Zuma’s exit has begun.”

Mmusi Maimane, leader of the DA, the biggest opposition party, said the ANC was steadily losing popular support.

“The ANC has lost support, but how much is because of Zuma, how much because of the economy, how much just due to sheer corruption? The current battle is not about the fitness of the president but about the soul of the ANC”, Maimane said.

The release of the report by the country’s public protector, an independent state office charged with uncovering maladministration, this month was a major blow.

It focused on Zuma’s close relationship with billionaire brothers Ajay, Atul and Rajesh Gupta, who run a business empire ranging from media to mining. Zuma has denied giving the Guptas undue influence and they have denied seeking it.

A campaign by Zuma allies to oust Praveen Gordhan, the respected finance minister, has rattled investors.

Though the ANC is still has massive support, the unprecedented loss of major municipalities to a coalition of opposition parties after elections in August has also worried many among the party’s “reformist” faction.

The ANC led the struggle against the racist and repressive apartheid regime and then took power in 1994 in South Africa’s first free elections.

Zuma’s enemies within the ANC are backed by increasing numbers of anti-apartheid veterans, trade unions, civil groups and business leaders.

The next national elections are due in 2019. External experts have warned ANC strategists that the party’s popularity was eroding fast.

But internal polls revealed that dissatisfaction with Zuma was only a minor factor for voters, with the ANC’s failure to deliver high-quality services such as water, schools, power and housing playing a greater role.